In a variety of technological contexts the need exists to remove heat from a plurality of closely positioned heat-generating elements. For instance, to maximize the longevity of semiconductor modules positioned on a card or board designed for installation in a computer, it is important that heat generated by the modules be effectively dissipated.
Systems for achieving such heat dissipation are known. For instance, Zushi et al. disclose in U.S. Pat. No. 4,837,663 (the "'663 patent") a system for cooling a plurality of semiconductor devices positioned on printed circuit boards mounted in a computer. The system of the '663 patent comprises a fan for causing air to flow through the rack on which the circuit boards are supported and a draft duct for dividing the air flow into a plurality of partial air flows.
Cooling systems of the type disclosed in the '663 patent generally provide satisfactory heat dissipation when used with relatively low power semiconductor devices and when such devices are packed on a circuit board such that a relatively large spacing exists between devices. However, such cooling systems do not provide adequate heat dissipation when used with relatively high power semiconductor devices due to the relatively large amount of heat such devices generate. Furthermore, cooling systems of the type disclosed in the '663 patent do not provide adequate heat dissipation when semiconductor devices are positioned on a circuit board in accordance with current packing densities.
It is believed that cooling systems of the type disclosed in the '663 patient do not provide adequate cooling when used with relatively high power semiconductor devices packed at relatively great densities, in part, due to the existence of an air boundary layer or "dead air" zone which is believed to exist adjacent the top surfaces of the semiconductor devices. Such "dead air" zone constitutes a planar region overlying the semiconductor devices where little or no air flow occurs. Due to the existence of such "dead air" zone, cooling air flowing over the semiconductor devices does not extract heat from the top surfaces of the devices as effectively as is desired. Furthermore, because of the "dead air" zone, cooling air does not tend to flow into the spaces between semiconductor devices. As a result, heat is not dissipated very effectively from the sides of the devices.
Systems are known for channeling the flow of cooling air provided adjacent semiconductor devices mounted on a card or circuit board so as to cause such air to diverge from its path of travel and flow into more direct contact with such devices. Such systems are disclosed, for instance, in U.S. Pat. Nos. 4,996,389 to Kajiwara et al. and 5,021,924 to Kieda et al. Unfortunately such systems do not tend to redirect the flow of cooling S air so as to cause such air to enter the spaces between the semiconductor devices. Instead, the air is merely redirected so as to flow over the top surfaces of such devices, with the result that the full cooling potential of the air is not utilized.
Other known apparatus for removing heat from semiconductor devices include heat-dissipating fins, as disclosed in U.S. Pat. No. 4,961,125 to Jordan et al. (the '125 patent), and "cold plates," as disclosed in U.S. Pat. No. 5,016,090 to Gaylon et al. Although fins of the type disclosed in the '125 patent tend to provide effective cooling of the semiconductor devices with which they are associated, they are often relatively expensive and frequently require more space than is desired. Conventional cool plates do not contain structure for redirecting the flow of air passing over the top surface of the cool plate so as to cause such air to flow into direct contact with the heat-generating devices engaging the bottom surface of the cool plate. Absent such structure, conventional cool plates do not provide the degree of cooling desired.